1. Field of the Invention
The present invention relates to an active matrix liquid crystal display in which a liquid crystal material forms bend configuration, and a method of manufacturing the same.
2. Description of the Related Art
A π cell mode and an optically compensated bend (OCB) mode are liquid crystal display modes capable of realizing a wide viewing angle and a high response speed. When an image is displayed on a liquid crystal display employing one of these display modes, the tilt angle of liquid crystal molecules near the back and front electrodes is changed while bend configuration is maintained. An image is displayed by using a retardation change of a liquid crystal layer caused by this tilt angle change.
Liquid crystal displays employing the π cell mode or OCB mode, however, have a disadvantage that a configurational transition of a liquid crystal material from splay configuration to bend configuration is necessary every time energizing the displays, and this initial transition process requires applying a voltage of a few volts or more between the back and front electrodes for from a few seconds to a few minutes. Such an initial transition process hinders applications of the n cell mode and OCB mode.
A technique which makes the initial transition process unnecessary is described by T. Konno et al. in “OCB-Cell Using Polymer Stabilized Bend Alignment”, ASIA DISPLAY '95, pp. 581-583. More specifically, a transition from splay configuration to bend configuration is caused by applying the initialization voltage to a nematic-phase mixture of an ultraviolet curing monomer and liquid crystal material. In this state, a polymer network is formed by irradiating the mixture with ultraviolet light.
In a liquid crystal cell obtained by this method, the liquid crystal material forms twisted configuration before energizing. At a certain voltage or more, the optical characteristics of twisted configuration and bend configuration are substantially equal, and a transition from twisted configuration to bend configuration is very fast. Accordingly, this liquid crystal cell requires no initial transition process.
Many liquid crystal displays which are required to have high image quality, however, use the active matrix driving method. When achieving the present invention, the present inventors have found that active matrix liquid crystal displays using the technique of T. Konno et al. readily cause display unevenness.